The present invention relates to a plasma processing apparatus that performs an etching process of a wafer as a processing target mounted on a sample stage provided in a processing chamber disposed inside a vacuum chamber using a plasma generated in the processing chamber, or a plasma processing method. In particular, the present invention relates to a plasma processing apparatus that processes a sample while supplying high-frequency power to an electrode inside a sample stage onto which a substrate-like sample such as a semiconductor wafer is mounted.
In manufacturing processes of forming a circuit of a semiconductor device on a sample such as a semiconductor wafer, a dry etching is performed to etch a film structure which is formed with a plurality of film layers disposed in advance on the semiconductor wafer using a plasma. In general, a plasma processing apparatus of performing such a dry etching is provided with a vacuum chamber having a certain degree of vacuum to generate a plasma and is configured to place a sample such as a wafer inside a processing chamber as an interior space and supply a processing gas so as to generate the plasma, and to etch a thin film forming a circuit gate or an insulating layer in a film structure along a mask layer by using a reactive particle and a charged particle formed in the plasma.
A plasma processing apparatus according to the related art is provided with: a processing chamber disposed inside a vacuum chamber in which a plasma is generated and a sample is placed; a gas supply device which is connected to the processing chamber and supplies a processing gas into the processing chamber; a vacuum pumping apparatus such as a turbo molecular pump which maintains pressure inside the processing chamber to a certain value; a sample stage which chucks and holds a semiconductor wafer, as a member to be processed, mounted onto the sample stage, using static electricity; a plasma generating device which supplies an electric field or a magnetic field for generating a plasma in the processing chamber; or the like. When particles of the processing gas supplied through an induction hole disposed on a ceiling surface of the processing chamber by the electric field or the magnetic field supplied by the plasma generating device excite to generate a plasma, an interaction occurs between a reactive particle in the plasma and a material of a film structure of a wafer surface thereby proceeding an etching process.
In recent years, along with an improvement of an integration degree of a semiconductor device, a demand increases for implementing a further fine process with higher accuracy, that is, improvement in the processing accuracy, and further, a demand increases for a process with higher throughput even when a film layer to be processed is etched at plural steps. In order to cope with such demands, it is required to realize an optimal processing condition in a short period of time during each etching at each of the plural steps, for example, to realize an optimal temperature of the wafer. In order to realize the optimal temperature without impairing throughput at the plural steps employed in different conditions, a configuration to change the temperature of the wafer or the sample stage on which the wafer is mounted in a short period of time to perform adjustment with favorable accuracy is necessary.
In order to change the temperature of the wafer in a short period of time, it is effective to reduce thermal capacity of an upper part of the sample stage on which the wafer is mounted as small as possible. For this, it is considered to shorten a distance between atop surface of the sample stage to be in contact with the wafer and a temperature adjustment unit such as a heater disposed in the sample stage to adjust temperature of the wafer or the sample stage, or a flow path to flow a heat exchange medium, or to increase efficiency in heat transfer between the wafer and the temperature adjustment unit by reducing the number of components configuring the upper part.
In a plasma processing apparatus of the related art, as a unit to achieve such an object, it has been considered to supply high-frequency power to a film-like electrode to which DC power is supplied to electrostatically chuck the wafer so as to form a bias potential on the wafer. As an example of the related art, JP-A-6-45285 has been known. In the related art, a plasma processing apparatus is disclosed in which a film-like electrode for electrostatic chuck disposed in a sample stage is divided into a plurality of electrodes when viewed from above and a voltage value of high-frequency power supplied to the plurality of electrodes is adjusted so as to decrease a variation in distribution of processing speed or a shape after processing in a direction of a top surface of the wafer, thereby allowing a variation in characteristics of an etching process to be within a predetermined range.